1. Field of the Invention
The present invention relates to a sound processor for surround system and a sound processing method.
2. Description of Related Art
In recent years, N.1 channel surround systems have spread to movie theaters and homes.
For example, in a movie theater, N speakers are installed in front, back, left and right of auditorium seats (listeners) such that the N speakers surround the auditorium seats. In this case, N is often several tens or so. Moreover, in the movie theater, a speaker exclusively for bass sound called a subwoofer is often installed in addition to the N speakers. Since the subwoofer is used to output sounds of gunfire, footsteps of dinosaurs or the like belonging to a limited range of sound frequencies, the subwoofer is counted as 0.1 channel, as one that is below one channel. The speakers enable the listeners to percept powerful sounds outputted from the speakers.
For example, in home use, N speakers are installed in front, back, left and right of a user (listener) such that the N speakers surround the listener. Since it is difficult to install a large-scale surround system like one in movie theaters in a house, N is five to seven or so, for example. In the case of N being five, five speakers are arranged in the left front, the front, the right front, the left rear, and the right rear (the left side, the center side, the right side, the surround left side, and the surround right side) of the listener, respectively.
FIG. 1 shows a general sound processor. FIG. 2 shows a N.1 channel surround system (N is an integer of five or more) to which the general sound processor is applied.
As shown in FIG. 1, the sound processor includes N speakers 101-1 to 101-N, a sound source 102, an additional sound source 103, a coefficient data input section 104, an additional sound processing section 105, and a sound superimposition section 106.
As shown in FIG. 2, the N speakers 101-1 to 101-N are arranged in a room such that the N speakers 101-1 to 101-N surround a listener 100. The N speakers 101-1 to 101-N are arranged based on a N.1 channel surround system.
The sound source 102 outputs sound signals. The additional sound source 103 outputs an additional sound signal.
The sound processor is given with coefficient data, and the coefficient data input section 104 inputs the coefficient data into the additional sound processing section 105. The coefficient data includes N coefficients. The N coefficients indicate volumes of sounds outputted from the N speakers 101-1 to 101-N based on the additional sound signal, respectively.
The additional sound processing section 105 generates N adjusted additional sound signals by multiplying the additional sound signal by the N coefficients, respectively.
The sound superimposition section 106 generates N superimposed sound signals by superimposing the N adjusted additional sound signals on the sound signals, respectively. The N speakers 101-1 to 101-N output sounds based on the N superimposed sound signals, respectively.
A method of superimposing sounds will be described in addition to the above-mentioned sound processor.
Japanese Laid Open patent Application (JP-A-Heisei 11-215078) discloses a mixer which combines arbitrarily a plurality of pieces of sound information inputted into the mixer and then outputs the results. The mixer includes an input channel device having a plurality of input channels, a bus-select switch device having a plurality of bus-select switches formed in a matrix, and an output channel device having a plurality of output channels. Below given is an exemplary case that first and second sound signals inputted into first and third input channels (input channels 1 and 3) of the plurality of input channels are mixed and the resulting superimposed sound signal is outputted from a third output channel (output channel 3) of the plurality of output channels. In this case, the first and second sound signals are superimposed by setting a bus-select switch of the first row and the second column of the matrix and a bus-select switch of the third row and the second column of the matrix (bus-select switches i12 and i32 of the plurality of bus-select switches) to on state. In the case of the mixer disclosed in Japanese Laid Open patent Application (JP-A-Heisei 11-215078), it is necessary to provide the bus-select switches between the input channels and the output channels. This may cause a problem of introducing enlargement of a circuit scale and an increase in sequence.
In the above-described sound processor, the additional sound signals are superimposed on the sound signals for all the speakers 101-1 to 101-N and all the speakers 101-1 to 101-N output superimposed sounds based on the resulting superimposed sound signals. For example, there is a case that additional sound is desired to be heard by the listener 100 from left and center directions with respect to the listener 100. Even in this case, the superimposed sounds each of which includes the sound based on the sound signal and the additional sound based on the additional sound signal superimposed on the sound signal are outputted from all the speakers 101-1 to 101-N. Such art has room to improve.